The histamine is a transmitter substance synthesized by the basophilic Granulocyte S (cells belonging to a variety of white globules).
Histamine is stored in the cells and is released in circumstances such as the reactions of Hypersensibilité.
Histamine causes a Sécrétion Gastric juice and of Hydrochloric acid, a relaxation of small the Artère S, a contraction of the Bronche S and Muscle S of the Intestin, a cardiac acceleration, a relaxation of the contractions of the Utérus.
Chemical propertiesHistamine involves a vasodilatation and a bronchoconstriction. In the stomach, it stimulates the secretion of HCl. From a chemical point of view, histamine is the 2 (4-imidazolyl) éthylamine and has as a formula C 5 H 9 NR 3. Histamine is synthesized by Décarboxylation Histidine (an amino-acid). This reaction is catalyzed by the Enzyme L-histidine décarboxylase. It is a amine vasoactive Hydrophile (from where the name). Certain forms of food poisonings are due to the conversion of histidine into histamine in broken up foodstuffs, like fish.
Histamine and allergiesHistamine plays a big role in the mechanisms of food intolerance, the allergy (it is responsible for allergic demonstrations such as the vasodilatations and the oedemas), of the anaphylaxie, urticaria, the ignitions and to increase during allergic reaction. The antihistamines are drugs which inhibit the histaminic receivers H1 (allergic demonstrations) and H2 (stomach), it exists indeed several sub-types of receivers histaminergic (H1, H2, H3, H4). By blocking the receivers of histamine, the antihistamines prevent histamine from acting.
Role of histamine in the central nervous systemHistamine is also a neuromodulator (module synaptic transmission) used by the neurons called rightly " neurons histaminergiques" (neurons which releases from histamine and which thus modulates the synaptic transmission between other neurons). One finds such neurons in a quite precise zone of the central nervous system: the hypothalamus and more precisely the posterior hypothalamus. These neurons histaminergic projètent largely in all the cerebral cortex and release histamine there what makes it possible to obtain a state of satisfactory awakening (histamine is not essential to the awakening but strongly contributes to it). Indeed, a deficit in this system histaminergic is probably responsible for the hypersomnie met in the narcolepsy (disease in which the individual reached of narcolepsy falls asleep suddenly and almost instantaneously). The role of histamine in the awakening also explains why the antihistamines (used against the allergy) cause a somnolence: they block the action of histamine. Histamine playing a part in the allergy the antihistamines thus decreases by them the symptoms (required effects) but block also the action of histamine in the awakening cortical (side effect: somnolence).
Food and Histamine
Rich foods in histamine
- the chocolate
- Certains cheeses the such Roquefort
- the marinaded fish the such herring
- the fish preserves of it (tuna, sardines)
- the faisandés game
- the brewers' yeast and the food fermented (wine, beer, sauerkraut)
- the pork-butchery
- fruits: mill, banana Khmer, pineapples, papaw and various tropical fruits
- the tomato
- the leguminous plants: dry pea, soya, lenses, broad beans, groundnuts
- fish and the shellfish
- alcoholic drinks
- the coffee
- the spices, of which cinnamon
- hazel nuts, nuts, the peanuts
- the sauerkraut
- egg yolk
- the fish
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